1 // RUN: %clang_cc1 -fsyntax-only -std=c++11 -pedantic -verify -fcxx-exceptions %s -fconstexpr-depth 128 -triple i686-pc-linux-gnu
2 
3 // A conditional-expression is a core constant expression unless it involves one
4 // of the following as a potentially evaluated subexpression [...]:
5 
6 // - this (5.1.1 [expr.prim.general]) [Note: when evaluating a constant
7 //   expression, function invocation substitution (7.1.5 [dcl.constexpr])
8 //   replaces each occurrence of this in a constexpr member function with a
9 //   pointer to the class object. -end note];
10 struct This {
11   int this1 : this1; // expected-error {{undeclared}}
12   int this2 : this->this1; // expected-error {{invalid}}
13   void this3() {
14     int n1[this->this1]; // expected-warning {{variable length array}}
15     int n2[this1]; // expected-warning {{variable length array}}
16     (void)n1, (void)n2;
17   }
18 };
19 
20 // - an invocation of a function other than a constexpr constructor for a
21 //   literal class or a constexpr function [ Note: Overload resolution (13.3)
22 //   is applied as usual - end note ];
23 struct NonConstexpr1 {
24   static int f() { return 1; } // expected-note {{here}}
25   int n : f(); // expected-error {{constant expression}} expected-note {{non-constexpr function 'f' cannot be used in a constant expression}}
26 };
27 struct NonConstexpr2 {
28   constexpr NonConstexpr2(); // expected-note {{here}}
29   int n;
30 };
31 struct NonConstexpr3 {
32   NonConstexpr3();
33   int m : NonConstexpr2().n; // expected-error {{constant expression}} expected-note {{undefined constructor 'NonConstexpr2'}}
34 };
35 struct NonConstexpr4 {
36   NonConstexpr4();
37   int n;
38 };
39 struct NonConstexpr5 {
40   int n : NonConstexpr4().n; // expected-error {{constant expression}} expected-note {{non-literal type 'NonConstexpr4' cannot be used in a constant expression}}
41 };
42 
43 // - an invocation of an undefined constexpr function or an undefined
44 //   constexpr constructor;
45 struct UndefinedConstexpr {
46   constexpr UndefinedConstexpr();
47   static constexpr int undefinedConstexpr1(); // expected-note {{here}}
48   int undefinedConstexpr2 : undefinedConstexpr1(); // expected-error {{constant expression}} expected-note {{undefined function 'undefinedConstexpr1' cannot be used in a constant expression}}
49 };
50 
51 // - an invocation of a constexpr function with arguments that, when substituted
52 //   by function invocation substitution (7.1.5), do not produce a core constant
53 //   expression;
54 namespace NonConstExprReturn {
55   static constexpr const int &id_ref(const int &n) {
56     return n;
57   }
58   struct NonConstExprFunction {
59     int n : id_ref(16); // ok
60   };
61   constexpr const int *address_of(const int &a) {
62     return &a;
63   }
64   constexpr const int *return_param(int n) { // expected-note {{declared here}}
65     return address_of(n);
66   }
67   struct S {
68     int n : *return_param(0); // expected-error {{constant expression}} expected-note {{read of variable whose lifetime has ended}}
69   };
70 }
71 
72 // - an invocation of a constexpr constructor with arguments that, when
73 //   substituted by function invocation substitution (7.1.5), do not produce all
74 //   constant expressions for the constructor calls and full-expressions in the
75 //   mem-initializers (including conversions);
76 namespace NonConstExprCtor {
77   struct T {
78     constexpr T(const int &r) :
79       r(r) {
80     }
81     const int &r;
82   };
83   constexpr int n = 0;
84   constexpr T t1(n); // ok
85   constexpr T t2(0); // expected-error {{must be initialized by a constant expression}} expected-note {{temporary created here}} expected-note {{reference to temporary is not a constant expression}}
86 
87   struct S {
88     int n : T(4).r; // ok
89   };
90 }
91 
92 // - an invocation of a constexpr function or a constexpr constructor that would
93 //   exceed the implementation-defined recursion limits (see Annex B);
94 namespace RecursionLimits {
95   constexpr int RecurseForever(int n) {
96     return n + RecurseForever(n+1); // expected-note {{constexpr evaluation exceeded maximum depth of 128 calls}} expected-note 9{{in call to 'RecurseForever(}} expected-note {{skipping 118 calls}}
97   }
98   struct AlsoRecurseForever {
99     constexpr AlsoRecurseForever(int n) :
100       n(AlsoRecurseForever(n+1).n) // expected-note {{constexpr evaluation exceeded maximum depth of 128 calls}} expected-note 9{{in call to 'AlsoRecurseForever(}} expected-note {{skipping 118 calls}}
101     {}
102     int n;
103   };
104   struct S {
105     int k : RecurseForever(0); // expected-error {{constant expression}} expected-note {{in call to}}
106     int l : AlsoRecurseForever(0).n; // expected-error {{constant expression}} expected-note {{in call to}}
107   };
108 }
109 
110 // DR1458: taking the address of an object of incomplete class type
111 namespace IncompleteClassTypeAddr {
112   struct S;
113   extern S s;
114   constexpr S *p = &s; // ok
115   static_assert(p, "");
116 
117   extern S sArr[];
118   constexpr S (*p2)[] = &sArr; // ok
119 
120   struct S {
121     constexpr S *operator&() const { return nullptr; }
122   };
123   constexpr S *q = &s; // ok
124   static_assert(!q, "");
125 }
126 
127 // - an operation that would have undefined behavior [Note: including, for
128 //   example, signed integer overflow (Clause 5 [expr]), certain pointer
129 //   arithmetic (5.7 [expr.add]), division by zero (5.6 [expr.mul]), or certain
130 //   shift operations (5.8 [expr.shift]) -end note];
131 namespace UndefinedBehavior {
132   void f(int n) {
133     switch (n) {
134     case (int)4.4e9: // expected-error {{constant expression}} expected-note {{value 4.4E+9 is outside the range of representable values of type 'int'}}
135     case (int)0x80000000u: // ok
136     case (int)10000000000ll: // expected-note {{here}}
137     case (unsigned int)10000000000ll: // expected-error {{duplicate case value}}
138     case (int)(unsigned)(long long)4.4e9: // ok
139     case (int)(float)1e300: // expected-error {{constant expression}} expected-note {{value +Inf is outside the range of representable values of type 'int'}}
140     case (int)((float)1e37 / 1e30): // ok
141     case (int)(__fp16)65536: // expected-error {{constant expression}} expected-note {{value +Inf is outside the range of representable values of type 'int'}}
142       break;
143     }
144   }
145 
146   constexpr int int_min = ~0x7fffffff;
147   constexpr int minus_int_min = -int_min; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
148   constexpr int div0 = 3 / 0; // expected-error {{constant expression}} expected-note {{division by zero}}
149   constexpr int mod0 = 3 % 0; // expected-error {{constant expression}} expected-note {{division by zero}}
150   constexpr int int_min_div_minus_1 = int_min / -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
151   constexpr int int_min_mod_minus_1 = int_min % -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range}}
152 
153   constexpr int shl_m1 = 0 << -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}}
154   constexpr int shl_0 = 0 << 0; // ok
155   constexpr int shl_31 = 0 << 31; // ok
156   constexpr int shl_32 = 0 << 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type 'int' (32}}
157   constexpr int shl_unsigned_negative = unsigned(-3) << 1; // ok
158   constexpr int shl_unsigned_into_sign = 1u << 31; // ok
159   constexpr int shl_unsigned_overflow = 1024u << 31; // ok
160   constexpr int shl_signed_negative = (-3) << 1; // expected-error {{constant expression}} expected-note {{left shift of negative value -3}}
161   constexpr int shl_signed_ok = 1 << 30; // ok
162   constexpr int shl_signed_into_sign = 1 << 31; // ok (DR1457)
163   constexpr int shl_signed_into_sign_2 = 0x7fffffff << 1; // ok (DR1457)
164   constexpr int shl_signed_off_end = 2 << 31; // expected-error {{constant expression}} expected-note {{signed left shift discards bits}} expected-warning {{signed shift result (0x100000000) requires 34 bits to represent, but 'int' only has 32 bits}}
165   constexpr int shl_signed_off_end_2 = 0x7fffffff << 2; // expected-error {{constant expression}} expected-note {{signed left shift discards bits}} expected-warning {{signed shift result (0x1FFFFFFFC) requires 34 bits to represent, but 'int' only has 32 bits}}
166   constexpr int shl_signed_overflow = 1024 << 31; // expected-error {{constant expression}} expected-note {{signed left shift discards bits}} expected-warning {{requires 43 bits to represent}}
167   constexpr int shl_signed_ok2 = 1024 << 20; // ok
168 
169   constexpr int shr_m1 = 0 >> -1; // expected-error {{constant expression}} expected-note {{negative shift count -1}}
170   constexpr int shr_0 = 0 >> 0; // ok
171   constexpr int shr_31 = 0 >> 31; // ok
172   constexpr int shr_32 = 0 >> 32; // expected-error {{constant expression}} expected-note {{shift count 32 >= width of type}}
173 
174   struct S {
175     int m;
176   };
177   constexpr S s = { 5 };
178   constexpr const int *p = &s.m + 1;
179   constexpr const int &f(const int *q) {
180     return q[0];
181   }
182   constexpr int n = (f(p), 0); // ok
183   struct T {
184     int n : f(p); // expected-error {{not an integral constant expression}} expected-note {{read of dereferenced one-past-the-end pointer}}
185   };
186 
187   namespace Ptr {
188     struct A {};
189     struct B : A { int n; };
190     B a[3][3];
191     constexpr B *p = a[0] + 4; // expected-error {{constant expression}} expected-note {{element 4 of array of 3 elements}}
192     B b = {};
193     constexpr A *pa = &b + 1; // expected-error {{constant expression}} expected-note {{base class of pointer past the end}}
194     constexpr B *pb = (B*)((A*)&b + 1); // expected-error {{constant expression}} expected-note {{derived class of pointer past the end}}
195     constexpr const int *pn = &(&b + 1)->n; // expected-error {{constant expression}} expected-note {{field of pointer past the end}}
196     constexpr B *parr = &a[3][0]; // expected-error {{constant expression}} expected-note {{array element of pointer past the end}}
197 
198     constexpr A *na = nullptr;
199     constexpr B *nb = nullptr;
200     constexpr A &ra = *nb; // expected-error {{constant expression}} expected-note {{cannot access base class of null pointer}}
201     constexpr B &rb = (B&)*na; // expected-error {{constant expression}} expected-note {{cannot access derived class of null pointer}}
202     static_assert((A*)nb == 0, "");
203     static_assert((B*)na == 0, "");
204     constexpr const int &nf = nb->n; // expected-error {{constant expression}} expected-note {{cannot access field of null pointer}}
205     constexpr const int *np1 = (int*)nullptr + 0; // ok
206     constexpr const int *np2 = &(*(int(*)[4])nullptr)[0]; // ok
207     constexpr const int *np3 = &(*(int(*)[4])nullptr)[2]; // expected-error {{constant expression}} expected-note {{cannot perform pointer arithmetic on null pointer}}
208 
209     struct C {
210       constexpr int f() const { return 0; }
211     } constexpr c = C();
212     constexpr int k1 = c.f(); // ok
213     constexpr int k2 = ((C*)nullptr)->f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced null pointer}}
214     constexpr int k3 = (&c)[1].f(); // expected-error {{constant expression}} expected-note {{member call on dereferenced one-past-the-end pointer}}
215     C c2;
216     constexpr int k4 = c2.f(); // ok!
217 
218     constexpr int diff1 = &a[2] - &a[0];
219     constexpr int diff2 = &a[1][3] - &a[1][0];
220     constexpr int diff3 = &a[2][0] - &a[1][0]; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
221     static_assert(&a[2][0] == &a[1][3], "");
222     constexpr int diff4 = (&b + 1) - &b;
223     constexpr int diff5 = &a[1][2].n - &a[1][0].n; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
224     constexpr int diff6 = &a[1][2].n - &a[1][2].n;
225     constexpr int diff7 = (A*)&a[0][1] - (A*)&a[0][0]; // expected-error {{constant expression}} expected-note {{subtracted pointers are not elements of the same array}}
226   }
227 
228   namespace Overflow {
229     // Signed int overflow.
230     constexpr int n1 = 2 * 3 * 3 * 7 * 11 * 31 * 151 * 331; // ok
231     constexpr int n2 = 65536 * 32768; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
232     constexpr int n3 = n1 + 1; // ok
233     constexpr int n4 = n3 + 1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
234     constexpr int n5 = -65536 * 32768; // ok
235     constexpr int n6 = 3 * -715827883; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
236     constexpr int n7 = -n3 + -1; // ok
237     constexpr int n8 = -1 + n7; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
238     constexpr int n9 = n3 - 0; // ok
239     constexpr int n10 = n3 - -1; // expected-error {{constant expression}} expected-note {{value 2147483648 is outside the range of }}
240     constexpr int n11 = -1 - n3; // ok
241     constexpr int n12 = -2 - n3; // expected-error {{constant expression}} expected-note {{value -2147483649 is outside the range of }}
242     constexpr int n13 = n5 + n5; // expected-error {{constant expression}} expected-note {{value -4294967296 is outside the range of }}
243     constexpr int n14 = n3 - n5; // expected-error {{constant expression}} expected-note {{value 4294967295 is outside the range of }}
244     constexpr int n15 = n5 * n5; // expected-error {{constant expression}} expected-note {{value 4611686018427387904 is outside the range of }}
245     constexpr signed char c1 = 100 * 2; // ok expected-warning{{changes value}}
246     constexpr signed char c2 = '\x64' * '\2'; // also ok  expected-warning{{changes value}}
247     constexpr long long ll1 = 0x7fffffffffffffff; // ok
248     constexpr long long ll2 = ll1 + 1; // expected-error {{constant}} expected-note {{ 9223372036854775808 }}
249     constexpr long long ll3 = -ll1 - 1; // ok
250     constexpr long long ll4 = ll3 - 1; // expected-error {{constant}} expected-note {{ -9223372036854775809 }}
251     constexpr long long ll5 = ll3 * ll3; // expected-error {{constant}} expected-note {{ 85070591730234615865843651857942052864 }}
252 
253     // Yikes.
254     char melchizedek[2200000000];
255     typedef decltype(melchizedek[1] - melchizedek[0]) ptrdiff_t;
256     constexpr ptrdiff_t d1 = &melchizedek[0x7fffffff] - &melchizedek[0]; // ok
257     constexpr ptrdiff_t d2 = &melchizedek[0x80000000u] - &melchizedek[0]; // expected-error {{constant expression}} expected-note {{ 2147483648 }}
258     constexpr ptrdiff_t d3 = &melchizedek[0] - &melchizedek[0x80000000u]; // ok
259     constexpr ptrdiff_t d4 = &melchizedek[0] - &melchizedek[0x80000001u]; // expected-error {{constant expression}} expected-note {{ -2147483649 }}
260 
261     // Unsigned int overflow.
262     static_assert(65536u * 65536u == 0u, ""); // ok
263     static_assert(4294967295u + 1u == 0u, ""); // ok
264     static_assert(0u - 1u == 4294967295u, ""); // ok
265     static_assert(~0u * ~0u == 1u, ""); // ok
266 
267     template<typename T> constexpr bool isinf(T v) { return v && v / 2 == v; }
268 
269     // Floating-point overflow and NaN.
270     constexpr float f1 = 1e38f * 3.4028f; // ok
271     constexpr float f2 = 1e38f * 3.4029f; // ok, +inf is in range of representable values
272     constexpr float f3 = 1e38f / -.2939f; // ok
273     constexpr float f4 = 1e38f / -.2938f; // ok, -inf is in range of representable values
274     constexpr float f5 = 2e38f + 2e38f; // ok, +inf is in range of representable values
275     constexpr float f6 = -2e38f - 2e38f; // ok, -inf is in range of representable values
276     constexpr float f7 = 0.f / 0.f; // expected-error {{constant expression}} expected-note {{division by zero}}
277     constexpr float f8 = 1.f / 0.f; // expected-error {{constant expression}} expected-note {{division by zero}}
278     constexpr float f9 = 1e308 / 1e-308; // ok, +inf
279     constexpr float f10 = f2 - f2; // expected-error {{constant expression}} expected-note {{produces a NaN}}
280     constexpr float f11 = f2 + f4; // expected-error {{constant expression}} expected-note {{produces a NaN}}
281     constexpr float f12 = f2 / f2; // expected-error {{constant expression}} expected-note {{produces a NaN}}
282     static_assert(!isinf(f1), "");
283     static_assert(isinf(f2), "");
284     static_assert(!isinf(f3), "");
285     static_assert(isinf(f4), "");
286     static_assert(isinf(f5), "");
287     static_assert(isinf(f6), "");
288     static_assert(isinf(f9), "");
289   }
290 }
291 
292 // - a lambda-expression (5.1.2);
293 struct Lambda {
294   int n : []{ return 1; }(); // expected-error {{constant expression}} expected-error {{integral constant expression}} expected-note {{non-literal type}}
295 };
296 
297 // - an lvalue-to-rvalue conversion (4.1) unless it is applied to
298 namespace LValueToRValue {
299   // - a non-volatile glvalue of integral or enumeration type that refers to a
300   //   non-volatile const object with a preceding initialization, initialized
301   //   with a constant expression  [Note: a string literal (2.14.5 [lex.string])
302   //   corresponds to an array of such objects. -end note], or
303   volatile const int vi = 1; // expected-note 2{{here}}
304   const int ci = 1;
305   volatile const int &vrci = ci;
306   static_assert(vi, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
307   static_assert(const_cast<int&>(vi), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}}
308   static_assert(vrci, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
309 
310   // - a non-volatile glvalue of literal type that refers to a non-volatile
311   //   object defined with constexpr, or that refers to a sub-object of such an
312   //   object, or
313   struct V {
314     constexpr V() : v(1) {}
315     volatile int v; // expected-note {{not literal because}}
316   };
317   constexpr V v; // expected-error {{non-literal type}}
318   struct S {
319     constexpr S(int=0) : i(1), v(const_cast<volatile int&>(vi)) {}
320     constexpr S(const S &s) : i(2), v(const_cast<volatile int&>(vi)) {}
321     int i;
322     volatile int &v;
323   };
324   constexpr S s; // ok
325   constexpr volatile S vs; // expected-note {{here}}
326   constexpr const volatile S &vrs = s; // ok
327   static_assert(s.i, "");
328   static_assert(s.v, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
329   static_assert(const_cast<int&>(s.v), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vi'}}
330   static_assert(vs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
331   static_assert(const_cast<int&>(vs.i), ""); // expected-error {{constant expression}} expected-note {{read of volatile object 'vs'}}
332   static_assert(vrs.i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
333 
334   // - a non-volatile glvalue of literal type that refers to a non-volatile
335   //   temporary object whose lifetime has not ended, initialized with a
336   //   constant expression;
337   constexpr volatile S f() { return S(); }
338   static_assert(f().i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
339   static_assert(((volatile const S&&)(S)0).i, ""); // expected-error {{constant expression}} expected-note {{read of volatile-qualified type}}
340 }
341 
342 // DR1312: The proposed wording for this defect has issues, so we ignore this
343 // bullet and instead prohibit casts from pointers to cv void (see core-20842
344 // and core-20845).
345 //
346 // - an lvalue-to-rvalue conversion (4.1 [conv.lval]) that is applied to a
347 // glvalue of type cv1 T that refers to an object of type cv2 U, where T and U
348 // are neither the same type nor similar types (4.4 [conv.qual]);
349 
350 // - an lvalue-to-rvalue conversion (4.1) that is applied to a glvalue that
351 // refers to a non-active member of a union or a subobject thereof;
352 namespace LValueToRValueUnion {
353   // test/SemaCXX/constant-expression-cxx11.cpp contains more thorough testing
354   // of this.
355   union U { int a, b; } constexpr u = U();
356   static_assert(u.a == 0, "");
357   constexpr const int *bp = &u.b;
358   constexpr int b = *bp; // expected-error {{constant expression}} expected-note {{read of member 'b' of union with active member 'a'}}
359 
360   extern const U pu;
361   constexpr const int *pua = &pu.a;
362   constexpr const int *pub = &pu.b;
363   constexpr U pu = { .b = 1 }; // expected-warning {{C99 feature}}
364   constexpr const int a2 = *pua; // expected-error {{constant expression}} expected-note {{read of member 'a' of union with active member 'b'}}
365   constexpr const int b2 = *pub; // ok
366 }
367 
368 // - an id-expression that refers to a variable or data member of reference type
369 //   unless the reference has a preceding initialization, initialized with a
370 //   constant expression;
371 namespace References {
372   const int a = 2;
373   int &b = *const_cast<int*>(&a);
374   int c = 10; // expected-note 2 {{here}}
375   int &d = c;
376   constexpr int e = 42;
377   int &f = const_cast<int&>(e);
378   extern int &g;
379   constexpr int &h(); // expected-note {{here}}
380   int &i = h(); // expected-note {{here}}
381   constexpr int &j() { return b; }
382   int &k = j();
383 
384   struct S {
385     int A : a;
386     int B : b;
387     int C : c; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
388     int D : d; // expected-error {{constant expression}} expected-note {{read of non-const variable 'c'}}
389     int D2 : &d - &c + 1;
390     int E : e / 2;
391     int F : f - 11;
392     int G : g; // expected-error {{constant expression}}
393     int H : h(); // expected-error {{constant expression}} expected-note {{undefined function 'h'}}
394     int I : i; // expected-error {{constant expression}} expected-note {{initializer of 'i' is not a constant expression}}
395     int J : j();
396     int K : k;
397   };
398 }
399 
400 // - a dynamic_cast (5.2.7);
401 namespace DynamicCast {
402   struct S { int n; };
403   constexpr S s { 16 };
404   struct T {
405     int n : dynamic_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{dynamic_cast}}
406   };
407 }
408 
409 // - a reinterpret_cast (5.2.10);
410 namespace ReinterpretCast {
411   struct S { int n; };
412   constexpr S s { 16 };
413   struct T {
414     int n : reinterpret_cast<const S*>(&s)->n; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}}
415   };
416   struct U {
417     int m : (long)(S*)6; // expected-warning {{constant expression}} expected-note {{reinterpret_cast}}
418   };
419 }
420 
421 // - a pseudo-destructor call (5.2.4);
422 namespace PseudoDtor {
423   int k;
424   typedef int I;
425   struct T {
426     int n : (k.~I(), 0); // expected-error {{constant expression}}
427   };
428 }
429 
430 // - increment or decrement operations (5.2.6, 5.3.2);
431 namespace IncDec {
432   int k = 2;
433   struct T {
434     int n : ++k; // expected-error {{constant expression}}
435     int m : --k; // expected-error {{constant expression}}
436   };
437 }
438 
439 // - a typeid expression (5.2.8) whose operand is of a polymorphic class type;
440 namespace std {
441   struct type_info {
442     virtual ~type_info();
443     const char *name;
444   };
445 }
446 namespace TypeId {
447   struct S { virtual void f(); };
448   constexpr S *p = 0;
449   constexpr const std::type_info &ti1 = typeid(*p); // expected-error {{must be initialized by a constant expression}} expected-note {{typeid applied to expression of polymorphic type 'TypeId::S'}}
450 
451   struct T {} t;
452   constexpr const std::type_info &ti2 = typeid(t);
453 }
454 
455 // - a new-expression (5.3.4);
456 // - a delete-expression (5.3.5);
457 namespace NewDelete {
458   int *p = 0;
459   struct T {
460     int n : *new int(4); // expected-error {{constant expression}}
461     int m : (delete p, 2); // expected-error {{constant expression}}
462   };
463 }
464 
465 // - a relational (5.9) or equality (5.10) operator where the result is
466 //   unspecified;
467 namespace UnspecifiedRelations {
468   int a, b;
469   constexpr int *p = &a, *q = &b;
470   // C++11 [expr.rel]p2: If two pointers p and q of the same type point to
471   // different objects that are not members of the same array or to different
472   // functions, or if only one of them is null, the results of p<q, p>q, p<=q,
473   // and p>=q are unspecified.
474   constexpr bool u1 = p < q; // expected-error {{constant expression}}
475   constexpr bool u2 = p > q; // expected-error {{constant expression}}
476   constexpr bool u3 = p <= q; // expected-error {{constant expression}}
477   constexpr bool u4 = p >= q; // expected-error {{constant expression}}
478   constexpr bool u5 = p < (int*)0; // expected-error {{constant expression}}
479   constexpr bool u6 = p <= (int*)0; // expected-error {{constant expression}}
480   constexpr bool u7 = p > (int*)0; // expected-error {{constant expression}}
481   constexpr bool u8 = p >= (int*)0; // expected-error {{constant expression}}
482   constexpr bool u9 = (int*)0 < q; // expected-error {{constant expression}}
483   constexpr bool u10 = (int*)0 <= q; // expected-error {{constant expression}}
484   constexpr bool u11 = (int*)0 > q; // expected-error {{constant expression}}
485   constexpr bool u12 = (int*)0 >= q; // expected-error {{constant expression}}
486   void f(), g();
487 
488   constexpr void (*pf)() = &f, (*pg)() = &g;
489   constexpr bool u13 = pf < pg; // expected-error {{constant expression}}
490   constexpr bool u14 = pf == pg;
491 
492   // If two pointers point to non-static data members of the same object with
493   // different access control, the result is unspecified.
494   struct A {
495   public:
496     constexpr A() : a(0), b(0) {}
497     int a;
498     constexpr bool cmp() const { return &a < &b; } // expected-note {{comparison of address of fields 'a' and 'b' of 'A' with differing access specifiers (public vs private) has unspecified value}}
499   private:
500     int b;
501   };
502   static_assert(A().cmp(), ""); // expected-error {{constant expression}} expected-note {{in call}}
503   class B {
504   public:
505     A a;
506     constexpr bool cmp() const { return &a.a < &b.a; } // expected-note {{comparison of address of fields 'a' and 'b' of 'B' with differing access specifiers (public vs protected) has unspecified value}}
507   protected:
508     A b;
509   };
510   static_assert(B().cmp(), ""); // expected-error {{constant expression}} expected-note {{in call}}
511 
512   // If two pointers point to different base sub-objects of the same object, or
513   // one points to a base subobject and the other points to a member, the result
514   // of the comparison is unspecified. This is not explicitly called out by
515   // [expr.rel]p2, but is covered by 'Other pointer comparisons are
516   // unspecified'.
517   struct C {
518     int c[2];
519   };
520   struct D {
521     int d;
522   };
523   struct E : C, D {
524     struct Inner {
525       int f;
526     } e;
527   } e;
528   constexpr bool base1 = &e.c[0] < &e.d; // expected-error {{constant expression}} expected-note {{comparison of addresses of subobjects of different base classes has unspecified value}}
529   constexpr bool base2 = &e.c[1] < &e.e.f; // expected-error {{constant expression}} expected-note {{comparison of address of base class subobject 'C' of class 'E' to field 'e' has unspecified value}}
530   constexpr bool base3 = &e.e.f < &e.d; // expected-error {{constant expression}} expected-note {{comparison of address of base class subobject 'D' of class 'E' to field 'e' has unspecified value}}
531 
532   // [expr.rel]p3: Pointers to void can be compared [...] if both pointers
533   // represent the same address or are both the null pointer [...]; otherwise
534   // the result is unspecified.
535   struct S { int a, b; } s;
536   constexpr void *null = 0;
537   constexpr void *pv = (void*)&s.a;
538   constexpr void *qv = (void*)&s.b;
539   constexpr bool v1 = null < (int*)0;
540   constexpr bool v2 = null < pv; // expected-error {{constant expression}}
541   constexpr bool v3 = null == pv; // ok
542   constexpr bool v4 = qv == pv; // ok
543   constexpr bool v5 = qv >= pv; // expected-error {{constant expression}} expected-note {{unequal pointers to void}}
544   constexpr bool v6 = qv > null; // expected-error {{constant expression}}
545   constexpr bool v7 = qv <= (void*)&s.b; // ok
546   constexpr bool v8 = qv > (void*)&s.a; // expected-error {{constant expression}} expected-note {{unequal pointers to void}}
547 }
548 
549 // - an assignment or a compound assignment (5.17); or
550 namespace Assignment {
551   int k;
552   struct T {
553     int n : (k = 9); // expected-error {{constant expression}}
554     int m : (k *= 2); // expected-error {{constant expression}}
555   };
556 
557   struct Literal {
558     constexpr Literal(const char *name) : name(name) {}
559     const char *name;
560   };
561   struct Expr {
562     constexpr Expr(Literal l) : IsLiteral(true), l(l) {}
563     bool IsLiteral;
564     union {
565       Literal l;
566       // ...
567     };
568   };
569   struct MulEq {
570     constexpr MulEq(Expr a, Expr b) : LHS(a), RHS(b) {}
571     Expr LHS;
572     Expr RHS;
573   };
574   constexpr MulEq operator*=(Expr a, Expr b) { return MulEq(a, b); }
575   Literal a("a");
576   Literal b("b");
577   MulEq c = a *= b; // ok
578 }
579 
580 // - a throw-expression (15.1)
581 namespace Throw {
582   struct S {
583     int n : (throw "hello", 10); // expected-error {{constant expression}}
584   };
585 }
586 
587 // PR9999
588 template<unsigned int v>
589 class bitWidthHolding {
590 public:
591   static const
592   unsigned int width = (v == 0 ? 0 : bitWidthHolding<(v >> 1)>::width + 1);
593 };
594 
595 static const int width=bitWidthHolding<255>::width;
596 
597 template<bool b>
598 struct always_false {
599   static const bool value = false;
600 };
601 
602 template<bool b>
603 struct and_or {
604   static const bool and_value = b && and_or<always_false<b>::value>::and_value;
605   static const bool or_value = !b || and_or<always_false<b>::value>::or_value;
606 };
607 
608 static const bool and_value = and_or<true>::and_value;
609 static const bool or_value = and_or<true>::or_value;
610 
611 static_assert(and_value == false, "");
612 static_assert(or_value == true, "");
613 
614 namespace rdar13090123 {
615   typedef __INTPTR_TYPE__ intptr_t;
616 
617   constexpr intptr_t f(intptr_t x) {
618     return (((x) >> 21) * 8);
619   }
620 
621   extern "C" int foo;
622 
623   constexpr intptr_t i = f((intptr_t)&foo - 10); // expected-error{{constexpr variable 'i' must be initialized by a constant expression}} \
624   // expected-note{{reinterpret_cast}}
625 }
626